Various procedures have been proposed for effecting reversible sterilization in the human female. Ideally, the method of choice should be a safe and effective means of contraception for the desired sterilization period which provides an acceptable probability of successful reversibility. Tubal sterilization methods characterized by varying degrees of reversibility include: tubal ligation procedures, as well as tubal occlusion by means of fulguration, application of clips, bands or rings, chemically-induced occlusion or implantation of intratubal plugs. Factors to be considered with any type of tubal sterilization method include the effect of the procedure on tubal tissue, as well as, potential tissue reaction, tube distortion, tissue sensitivity, risk of infection, damage during installation and removal of the sterilization device and necessity for surgical reanastomosis to restore tubal patency.
One known method of tubal occlusion involves the application of external clips to the fallopian tubes. A major drawback of the use of such clips is that the portion of the tube which is under direct pressure of the clip becomes crushed. Reversal of this sterilization method thus requires surgical excision of the necrosed section and reanastomosis of the remaining intact portions of the tube. When the clip pressure is high, the possibility of irreversible tissue damage becomes a concern due to continued interruption of blood supply to the involved tissue. The external clips may also expand with time, exert insufficient pressure due to tissue shrinkage, or become dislodged, thus allowing the tube to reopen. If the clips are made of metal materials, the possibility of tissue reaction must also be considered.
In an attempt to avoid various problems inherent in the method of clip compression of the fallopian tubes, the use if intratubal plugs has been proposed. A major consideration prompted by this tubal occulsion method is that the plug material be nontoxic and non-irritating to the surrounding tissue. The use of a plug alone, however, is not fully effective in all cases due to various factors such as tissue wall thickness shrinkage with time, ultimately leading to axial slippage of the plug.
The problem of maintaining complete tubal occlusion has been approached through the use of suture material tied around that portion of the tube containing an internal plug. The goal of this method is to effect compression of the single layer of tubal tissue located between the suture and the plug, "A Tubal Occlusive Device in Monkeys", In Sciarra, J. J., Zatuchni, G. I., Spiedel, J. J. (eds) Reversal of Sterilization, Harper & Row, pp. 226 (1977). With the use of sutures, comes the problem of tissue reaction to a given suture material. The suture/plug combination also poses installation as well as removal problems. For example, the suture material, over time, may become buried in the wall of the tube and subsequent plug removal necessitates cutting of the tissue. The fibrin which overgrows any foreign material in the peritoneal cavity can ultimately bury the suture material. Removal of the suture material most often causes significant damage of the tube tissue. Tearing or major disruption of the plug site has also been observed in some cases. In many instances, the suture material can cut through the tube during the removal process.
Steptoe has proposed the use of a solid silastic intratubal device having a nylon thread core, "The Potential Use of Intratubal Stents for Reversible Sterilization", In Sciarra, J. J., Droegemueller, W., Spridel, J. J. (eds) Advances in Female Sterilization Techniques, Harper & Row, pp. 91 (1976). The intratubal stent averages a length of 4 cm or 6 cm. and has protuberances at fixed intervals. Between a given pair of protuberances, an external tantalum locking clip is applied. Drawbacks of the device are that a high degree of technical skill is required for insertion of the device and specially designed instruments must be used for implantation.